Estimating the maximum allowable annular pressure (Pmax) is a critical stage in horizontal directional drilling (HDD) design to prevent inadvertent returns and avoid damage to nearby structures. To aid in the accuracy of this estimation, the University of Alberta completed a comparative analysis of existing analytical models for estimating Pmax, revealing significant variability in the results and consequent uncertainty in determining this parameter. A detailed evaluation of the models’ assumptions and derivations led to the development of a Decision-Making Framework, validated using data from a case study reporting annular pressures at failure. The proposed framework offers practitioners a structured approach to selecting the most appropriate model based on specific soil characteristics, thereby reducing uncertainty associated with inter-model variability. This research provides a tool for improving the reliability of Pmax predictions in HDD applications. 

Presenter: Mikaela Rocha

Mikaela Rocha recently graduated with a Master of Science in Underground Trenchless Construction from the University of Alberta. During her studies, she worked as a Graduate Research Assistant and Teaching Assistant. She is currently working as an Engineer-in-Training (EIT) at Stantec. Prior to her graduate program, Mikaela worked for five years in a professional capacity, serving as a Lab Instructor, and contributing to various engineering projects, including foundation design for wastewater treatment plants and slope stability analysis for highway construction projects.